@samitouri / QOSamiQemu / commits / 731525c276

plugins: use int64_t for the syscall filter return value

The syscall return value passed back through the syscall filter callback is semantically signed: negative values encode errno codes. Declaring the sysret pointer as uint64_t * is therefore misleading and forces callers to launder the value through an unsigned temporary. Change the sysret pointer to int64_t * across the public plugin API typedef (qemu_plugin_vcpu_syscall_filter_cb_t), the internal qemu_plugin_vcpu_syscall_filter() prototypes and stub, its implementation in plugins/core.c, the linux-user caller, and the in-tree example plugins. Signed-off-by: Ziyang Zhang <functioner@sjtu.edu.cn> Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com> Link: https://lore.kernel.org/qemu-devel/20260618082426.790315-2-functioner@sjtu.edu.cn Signed-off-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>

Ziyang Zhang committed Jun 18, 2026 at 16:24 UTC 731525c27607bbe392abe3b8be2bce3ab65ae4f5

6 files changed +7 -7

include/plugins/qemu-plugin.h

+1 -1

@@ -871,7 +871,7 @@ typedef bool

871 int64_t num, uint64_t a1, uint64_t a2,

872 uint64_t a3, uint64_t a4, uint64_t a5,

873 uint64_t a6, uint64_t a7, uint64_t a8,

874 - uint64_t *sysret,

874 + int64_t *sysret,

875 void *userdata);

876

877 /**

include/qemu/plugin.h

+2 -2

@@ -172,7 +172,7 @@ bool

172 qemu_plugin_vcpu_syscall_filter(CPUState *cpu, int64_t num, uint64_t a1,

173 uint64_t a2, uint64_t a3, uint64_t a4,

174 uint64_t a5, uint64_t a6, uint64_t a7,

175 - uint64_t a8, uint64_t *sysret);

175 + uint64_t a8, int64_t *sysret);

176

177 void qemu_plugin_vcpu_mem_cb(CPUState *cpu, uint64_t vaddr,

178 uint64_t value_low,

@@ -288,7 +288,7 @@ static inline bool

288 qemu_plugin_vcpu_syscall_filter(CPUState *cpu, int64_t num, uint64_t a1,

289 uint64_t a2, uint64_t a3, uint64_t a4,

290 uint64_t a5, uint64_t a6, uint64_t a7,

291 - uint64_t a8, uint64_t *sysret)

291 + uint64_t a8, int64_t *sysret)

292 {

293 return false;

294 }

linux-user/syscall.c

+1 -1

@@ -14619,7 +14619,7 @@ static bool send_through_syscall_filters(CPUState *cpu, int num,

14619 abi_long arg7, abi_long arg8,

14620 abi_long *sysret)

14621 {

14622 - uint64_t sysret64 = 0;

14622 + int64_t sysret64 = 0;

14623 bool filtered = qemu_plugin_vcpu_syscall_filter(cpu, num, arg1, arg2,

14624 arg3, arg4, arg5, arg6,

14625 arg7, arg8, &sysret64);

plugins/core.c

+1 -1

@@ -573,7 +573,7 @@ bool

573 qemu_plugin_vcpu_syscall_filter(CPUState *cpu, int64_t num, uint64_t a1,

574 uint64_t a2, uint64_t a3, uint64_t a4,

575 uint64_t a5, uint64_t a6, uint64_t a7,

576 - uint64_t a8, uint64_t *sysret)

576 + uint64_t a8, int64_t *sysret)

577 {

578 struct qemu_plugin_cb *cb, *next;

579 enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_SYSCALL_FILTER;

tests/tcg/plugins/setpc.c

+1 -1

@@ -27,7 +27,7 @@ static bool vcpu_syscall_filter(unsigned int vcpu_index,

27 int64_t num, uint64_t a1, uint64_t a2,

28 uint64_t a3, uint64_t a4, uint64_t a5,

29 uint64_t a6, uint64_t a7, uint64_t a8,

30 - uint64_t *sysret, void *userdata)

30 + int64_t *sysret, void *userdata)

31 {

32 if (num == MAGIC_SYSCALL) {

33 if (a1 == SETPC) {

tests/tcg/plugins/syscall.c

+1 -1

@@ -176,7 +176,7 @@ static bool vcpu_syscall_filter(unsigned int vcpu_index,

176 int64_t num, uint64_t a1, uint64_t a2,

177 uint64_t a3, uint64_t a4, uint64_t a5,

178 uint64_t a6, uint64_t a7, uint64_t a8,

179 - uint64_t *sysret, void *userdata)

179 + int64_t *sysret, void *userdata)

180 {

181 /* Special syscall to test the filter functionality. */

182 if (num == 4096 && a1 == 0x66CCFF) {